const m = require('./11.自定义模块')
console.log(m); // 打印结果： { username: 'zs', sayHello: [Function (anonymous)] }
// 暴露age 私有成员变量后，打印结果为：{ username: 'zs', sayHello: [Function (anonymous)], age: 12 }
// 让module.exports 指向一个新的对象后，打印结果为；{ nickname: '小黑', sayHi: [Function: sayHi] }